This invention relates to an improved method of forming an adhesive patch for applying medication to the skin.
Several kinds of patch devices have been used in the past for applying medication to the skin. For example, U.S. Pat. No. 4,675,009 describes a drug dispensing device for transdermal delivery of medication in which a natural or synthetic polysaccharide or synthetic polymer functions as a non-biodegradable adhesive reservoir. These patches, while very good, are so thick and cumbersome that users complain of their appearance and the discomfort associated with their use. Another deficiency is found in analgesic patch products that contain a rubber sheet backing which occludes the skin, making moisture evaporation virtually impossible.
One important object of the present invention is to provide a non-occlusive analgesic patch, i.e., one which will enable moisture vapor on the surface of the skin to evaporate through the patch so as to prevent the undesired accumulation of moisture which, if it occurred, could cause the patch to fall off or even facilitate the growth of bacteria beneath the patch.
Another objective of the present invention is to provide a much lighter, more flexible and less obtrusive patch while still providing excellent sustained release properties during eight hours or more of use.
Another more specific object is to find a way to enable the backing of the adhesive tape itself to serve as a reservoir for the sustained release of a medication to be applied topically into the skin.
Still another more specific object is to unify a porous backing and a hydrophilic pressure-sensitive hydrocolloidal dispersion which serves as a reservoir for medication so as to provide sustained release of the medication while reducing the thickness and bulk of the patch and improving its flexibility.
A further more specific object of the present invention is to provide a more comfortable and less obtrusive topical analgesic patch for the temporary relief of pain including arthritis pain, backaches as well as muscular aches and strains.
Yet another object is to provide an improved method of combining the porous backing and the hydrocolloidal medication-containing pressure-sensitive adhesive reservoir during manufacture.
These and other more detailed and specific objects of the present invention will be better understood by reference to the following figures and detailed description which illustrate by way of example but a few of the various forms of the invention within the scope of the appended claims.
Briefly, the present invention provides a non-occlusive medication patch to be applied to the skin. It includes a porous self-supporting backing layer to give the patch the required integrity and strength by acting as a supporting framework for other components, and a flexible hydrophilic pressure-sensitive adhesive reservoir comprising a hydrocolloidal gel for the sustained release of medication to be absorbed topically through the skin into the body of a patient. The reservoir has two portions: first, an external coating layer with an exposed lower skin-contacting surface that forms a pressure-sensitive bond with the skin, and second, an upper internal portion which infiltrates the porous backing and becomes solidified therein after being applied so that the reservoir and the backing are unified, enabling the backing itself to act as a storage location for the medication-containing reservoir. In this way, the medication within the reservoir migrates over time from within the backing through the lower coating layer and passes through the skin to provide sustained release of the medication into the body of a patient.
The reservoir comprises a hydrocolloidal dispersion of a natural or synthetic gel-forming polymer, a hydrophilic adhesive, a hydrophilic humectant and a biomedically active medication, i.e., a medicament, dispersed throughout the reservoir including both the external portion and the internal portion that infiltrates the porous backing.
The invention provides a comfortable, highly flexible patch that is thinner than prior patches, conforms to the body contours, is better tolerated by patients, and is considered by patients to be more unobtrusive. The invention provides outstanding results as a non-occlusive analgesic patch that can be adhered to the skin to release an analgesic for the relief of pain including arthritis pain, backache as well as muscular aches and strains. In such an application, the analgesic comprises trolamine salicylate, menthol salicylate, menthol, camphor, eucalyptus oil or spearmint oil, or a combination thereof.
The invention will be better understood by reference to the following specification and accompanying drawings.